Search for associated production of a Z boson with a single top quark and for tZ flavour-changing interactions in pp collisions at √{s}=8 TeV

Sirunyan, A. M.; Lucchini, M. T.; Lourenço, C.; Lecoq, P.; Lange, C.; Krammer, M.; Kousouris, K.; Kortelainen, M. J.; Kornmayer, A.; Knünz, V.; Kirschenmann, H.; Kieseler, J.; Janot, P.; Innocente, V.; Hegeman, J.; Harris, P.; Guthoff, M.; Gundacker, S.; Gulhan, D.; Glege, F.; Girone, M.; Gill, K.; Gigi, D.; Funk, W.; Fulcher, J.; Franzoni, G.; Fartoukh, S.; Everaerts, P.; Elliott-Peisert, A.; Dupont, N.; Dünser, M.; Duggan, D.; du Pree, T.; Dorney, B.; Dobson, M.; Di Marco, E.; De Roeck, A.; De Gruttola, M.; David, A.; Daponte, V.; Dabrowski, A.; d'Enterria, D.; Chen, Y.; Cerminara, G.; Cepeda, M.; Castello, R.; Camporesi, T.; Botta, C.; Bocci, A.; Bloch, P.; Barney, D.; Ball, A. H.; Baillon, P.; Bachtis, M.; Auzinger, G.; Auffray, E.; Abbaneo, D.; Vilar Cortabitarte, R.; Vila, I.; Trevisani, N.; Scodellaro, L.; RuizJimeno, A.; Rodrigo, T.; Piedra Gomez, J.; Matorras, F.; Martinez Rivero, C.; Marco, J.; Lopez Virto, A.; Gomez, G.; Garcia-Ferrero, J.; Fernandez, M.; Curras, E.; Calderon, A.; Cabrillo, I. J.; Vizan Garcia, J. M.; Suárez Andrés, I.; Sanchez Cruz, S.; Palencia Cortezon, E.; González Fernández, J. R.; Gonzalez Caballero, I.; Fernandez Menendez, J.; Cuevas, J.; Moran, D.; Missiroli, M.; de Trocóniz, J. F.; Soares, M. S.; Romero, L.; Redondo, I.; Quintario Olmeda, A.; Puerta Pelayo, J.; Pérez-Calero Yzquierdo, A.; Navarro De Martino, E.; Josa, M. I.; Hernandez, J. M.; Goy Lopez, S.; Gonzalez Lopez, O.; Garcia-Abia, P.; Fouz, M. C.; Flix, J.; Fernández Ramos, J. P. et al.
Bibliographical reference

Journal of High Energy Physics, Volume 2017, Issue 7, article id.3, 43 pp.

Advertised on:
7
2017
Number of authors
2233
IAC number of authors
1
Citations
21
Refereed citations
19
Description
A search for the production of a single top quark in association with a Z boson is presented, both to identify the expected standard model process and to search for flavour-changing neutral current interactions. The data sample corresponds to an integrated luminosity of 19.7 fb-1 recorded by the CMS experiment at the LHC in proton-proton collisions at √{s}=8 TeV. Final states with three leptons (electrons or muons) and at least one jet are investigated. An events yield compatible with tZq standard model production is observed, and the corresponding cross section is measured to be σ(pp → tZq → ℓνb ℓ + ℓ -q) = 10 - 7 + 8 fb with a significance of 2.4 standard deviations. No presence of flavour-changing neutral current production of tZq is observed. Exclusion limits at 95% confidence level on the branching fractions of a top quark decaying to a Z boson and an up or a charm quark are found to be ℬ(t → Zu) < 0.022% and ℬ(t → Zc) < 0.049%.
Type